Two phase fast breaking foam pressurized hair waving composition



United States Patent 3,099,603 TWO PHASE FAST BREAKING FOAM PRES SURIZED HAIR WAVING CQMPQSI'IION Robert D. Banker, Cincinnati, and Preston W. Grounds and Robert A. Cody, Springfield Township, Hamilton County, Ohio, assignors to The Procter & Gamble Company, Cincinnati, Qhio, a corporation of Ohio No Drawing. Filed June 13, 1960, Ser. No. 35,393

17 Claims. (til. 167--87.1)

This invention relates to compositions packaged in pressurized containers for the cold permanent waving of hair. The two liquid phase composition contains a vapor pressure depressant and is dispensed in the form of a fast breaking foam.

Cold permanent waving of hair is accomplished by contacting the hair with some chemical composition which will soften and plasticize it at room temperature. According to the present understanding in the art, such chemical compositions reduce the keratin structure of the hair, thereby breaking disulfide linkages. While the hair tresses are mechanically held in a new configuration, the disulfide linkages are restored by oxidation to fix the tresses in the new configuration.

In a conventional home waving procedure, the hair is first shampooed. After rinsing and removal of excess water, the individual hair tresses are saturated with reducing lotion before being wound on a curler or mandrel. The individual hair tresses, after having been Wound on the mandrel, are again saturated with reducing lotion. After a suitable period of time, the reducing lotion is removed from the hair with a water rinse; and the reduced hair, while still wound on the mandrel, is fixed by application of a chemical or by air oxidation. In the pin curl procedure, a few tresses saturated with lotion are formed on curlers as described, and the remainder are wound around a finger without prior saturation with lotion. The latter curls, held by bobby pins, are then, along with those on curlers, saturated with lotion. These curls are subsequently treated in the same way as those held on curlers.

In most commonly employed home waving procedures, the waving lotion is manually applied to the hair in the initial saturation step and again in the resaturation step after the hair has been wound on mandrels. A cotton pad or sponge which is repeatedly saturated by being dipped into the lotion is used as an applicator. The disadvantages inherent in such a procedure are readily apparent. The independent saturation of each individual hair tress, performed before and after winding on the mandrel, is both tedious and time consuming. Most modern hair waving lotions have an alkalinity above pH 9 and may behave as irritants when repeatedly brought into direct contact with the skin of sensitive individuals. The commonly employed methods for applying waving lotion provide opportunity for prolonged and repeated contact of this alkaline solution with the hands as the subject saturates the applicator and then applies the applicator to the hair. Furthermore, if not carefully applied, the run-off of lotion on the scalp and down the hands and wrists may be discomforting.

Recently, attempts have been made to eliminate some of the opportunities for the lotion to contact the hands by applying the lotion directly from a plastic squeeze bottle. A comb-tip may be, used in the initial saturation step. This method does not eliminate the dripping of excess lotion from the tresses and requires the user to transfer the lotion solution from the glass package in which it is supplied to the plastic bottle. A further development has been to provide a catch tray which can be held under a wound curl to catch the excess lotion as it runs off. The catch tray cannot be used in the initial saturation and demands considerable manipulative skill from a woman who is waving her own hair.

The volatility and susceptibility to oxidation of the active ingredients in many of the conventional hair waving lotions make the ordinary methods of commercial packaging inappropriate for a container of lotion which can be used and stored repeatedly without loss of activity. A type of packaging then, which will enable alternate use and storage should enjoy widespread consumer acceptance for touch-up Waves as well as for periodic full Wav- Pressurized containers or aerosol packages are well known and have been widely employed for packaging many products for household purposes. In spite of its recognized advantages in other areas, this packaging technique has not yet found widespread commercial usage in the field of cold permanent waving, not because of technical packaging difficulties, but because of the inherent demands of the cold waving technique. Even with the conventional hair Waving procedures described hereinbefore, it is difiicult to achieve the requisite uniform saturation of the hair with lotion. The outside of a wound tress may receive a heavy concentration of the lotion, while the portion of the hair inside a wound curl may receive a much smaller amount. As a result, portions of the hair may be damaged by the too high concentration, and other parts of the hair may not be redced at all because they are not contacted by sufficient lotion to break the disulphide bonds. The usual aerosol methods which might be used to dispense hair waving lotion as a foam or mist are by their very nature less able to meet the demands of cold hair waving than is the conventional technique. On the one hand, a foam acts as a physical impedimeut to the penetration of the reducing agent into the hair. On the other hand, a mist is unsatisfactory because of the wide diffusion of the hair waving lotion; most lotions are, to some individuals, unpleasant in odor and they may stain clothing.

The dispensing of products such as shaving cream and toothpaste as foams from pressurized containers is shown in Spitzer et al., in US. Patent 2,655,480. The contents of the package exist in the form of an emulsion and are discharged as a stable foam.

A first group of objects of this invention is: (l) to provide compositions packed in pressurized containers which make possible an improved method for waving hair, and (2) to provide packaged compositions which can be used for more than one wave without deterioration between uses. The improved method eliminates manual applica tion of waving lotion to the hair, thereby reducing the possibility of skin irritation which may result from the contact of highly alkaline waving lotion with the hands; and the improved method eliminates run-ofi of excess lotion from the hair.

These objects are achieved by a composition which is discharged as a f=ast-breaking foam, i.e., as an unstable foam which substantially completely breaks or collapses to a liquid promptly after discharge. This fast-breaking property permits the composition to be applied with the ease of a foam; and it achieves the requisite penetrability of a liquid. The limitations of both foam and liquid are eliminated at the same time. The application of the lotion as an unstable foam prevents run-off (and yet permits the lotion to return fairly rapidly to a fluid state which will be absorbed by the hair tress. The foam collapses at about the same rate at which the fluid penetnates the hair tress.

In order to achieve a fast-breaking foam the composition of the product must be correct. A most important requirement is that at the time of application propellant be finely dispersed throughout the composition. A true solution, that is, a molecular dispersion, is ideal in degree of dispersion and stability. However, propellants in general are not very soluble in aqueous solutions, particularly those containing keratin-reducing agents. It is therefore diflicult to dissolve enough of the usual propellants to give a satisfactory product or else it is necessary to add considerable quantities of a mutual solvent for the propellant in the aqueous liquid. For example, alcohol is effective; but it possesses the disadvantage of being inflammable if used in excess. It is, of course, more expensive than water. A satisfactorily fine dispersion of propellant in product can be achieved by an emulsion. However, it is difficult to formulate emulsions which are permanently stable. The presence of an emulsifying agent which can be deleterious to the hair wave results or which might react with the active hair waving agent is usually required. Most surface active agents or emulsifiers in concentrations above a few percent cause in combination with the keratin-reducing agent a decrease of mildness of the waiving lotion. The use of two liquid phase compositions in pressurized packages is well known. For example, Eaton in U.S. Patent 2,728,495 shows an aqueous liquid phase floating on top of the propellant liquid phase. His composition was not discharged as a foam. If the compositional Variables were properly adjusted, such a two phase system might discharge as a foam for a few seconds after violent agitation; but it would not continue to discharge as a foam for long because of the rapidity with which the propellant phase separates from the lighter aqueous phase.

If the essential requirement of having propellant finely dispersed in the product (at the time of discharge is satisfied by using a propellant with sufiicient solubility, disadvantages relating to the pressure prevailing in the package may be encountered which are preferably avoided. In may cases in which propellants which are highly soluble are used, only a small quantity of propellant ordinarily can be put in the package containing an aqueous phase at pressures usually considered safe. Under ideal conditions, such a package containing a small amount of highly soluble propellant may prove entirely satisfactory, but if there is slow leakage or if propellant is accidentally discharged from the pacleage without product, then the quantity of the propellant will be insufficient to properly discharge the product from the package in the form of a sufiicient amount :of fast breaking foam. It is ordinarily preferable not to add more propellant to overcome these disadvantages because the pressure in the package would be higher than is usually desired. The accuracy required to package a sufiicient amount of the usualhighly soluble propellants, without exceeding pressures which are ordinarily observed, assuming that none would be lost by leakage or accidental discharge, would be so great that commercially feasible production would be difiicult. A mutual solvent can be added to increase the solubility of the propellant in the aqueous phase; but, as has been mentioned before, there are disadvantages inherent in the addition of such solvent. High pressures in the package are ordinarily undesirable, particularly with conventional containers, since they may lead to excessive leakage of propellant from the package and limit the type of package that can be employed under accepted safety conditions.

If the pressure problem could be solved or ignored, such as by use of very strong containers or when high storage temperatures are not encountered, merely using a sufiicient quantity of a propellant that has high solubility in the aqueous phase does not necessarily result in a stable hair waving product having desirable fast breaking foaming characteristics. For example, it has been found that if the propellant is too soluble in the aqueous phase, no foam, fast breaking or otherwise, is formed. Other highly soluble propellants have prohibitive vapor pressures or are hydrolytically unstable.

A second group of objects is: (l) to provide a cold permanent waving composition having the advantages which result from discharge as a fast-breaking foam without the necessity of adding an alcoholic solvent or excessive amounts of an emulsifier and (2) to provide a pressurized cold permanent waving composition preferably having a reduced vapor pressure which makes possible a larger charge of propellant which performs satisfactorily, has less tendency for leakage and permits lower pressure packaging.

This second group of objects is accomplished by providing a cold permanent waving composition, which exists in the package in two liquid phases, and in which a specified propellant is used, preferably in combination with a vapor pressure depressant as hereinafter more fully described. The keratin-reducing agent is predominantly in an aqueous phase; and the second phase is predominantly propellant and, when included, vapor pressure depressant. However, (all constituents are partitioned between the two phases as would be expected from physical-chemical principles. Part of the propellant and other volatile constituents are in the vapor space of the package.

In brief this invention is a cold hair waving composi. tion packaged in a pressurized container and comprising a keratin reducing agent in aqueous solution, a specified propellant, a surface active agent, and preferably a vapor pressure depressant. In the package, the composition is in the form of two liquid phases and a vapor phase. The composition is discharged as an unstable foam which substantially completely collapses to a liquid promptly after discharge.

The objects of this invention can be accomplished by using, as the specified propellant, difluoroethane or monochlorodifiuoroethane. When difluoroethane is used, it is preferably used either with enough vapor pressure depressant to provide a package pressure depressed to a desirable range, as hereinafter described, or with enough vapor pressure depressant not only to provide a desirable pressure but to adjust the densities of the two liquid phases of the composition to substantially the same value, also as hereinafter described. In the latter case, wherein the densities of the two liquid phases are balanced, monochlorodifluoroeth'ane also can be used as the specified propellant. When the densities of the two liquid phases are balanced, they become readily mixable and the aforementioned requirement for a fine dispersal of propellant in the product is easily obtained by preparatory mixing. When monochlorodifluoroethane is used as the specified propellant without a vapor pressure depressant (for example, when it is not necessary to avoid high pressures, e.g., by use of strong containers or absence of high temperatures) fine dispersal of propellant is easily obtained by preparatory mixing. When vapor pressure depressants are used with monochlorcdifluoroethane, however, balancing of the liquid phase densities is necessary to provide a satisfactory product. However, when difluoroethane is used as the propellant, mixing is not necessary whether or not vapor pressure depressants are used. The necessity for preparatory mixing, while it is a relatively easy and minor step, requires extra instruction for the user, and if the user forgets to perform the mixing step, the results may not be as expected. However, even though preparatory mixing is not necessary when difluoroethane is used as the propellant in the compositions of this invention to obtain good results therefrom, it is not intended that the product should not be mixed. Users often shake pressurized products by habit and shaking may be desirable to distribute more evenly any perfume present in the composition.

Low molecular weight water-soluble mercaptans containing another functional group, such as carboxyl, hydroxyl, or amide, in addition to the mercaptan group, are suitable keratin-reducing agents for the" waving lotions of this invention. The mercapto-alkanoic acids described in U.S. Patent 2,736,323 are preferred keratin-reducing substances because of their effectiveness and because they foam, with or without preparatory mixing, the propellant used in the compositions of this invention should have a solubility in water at 70 F. greater than about 0.05 weight percent. However, no foam, fast breaking or otherwise, is formed if the propellant used has a solubility too great, i.e., greater than about 0.40 weight percent at 70 F. The importance of the correct propellant solubility on foam breaking time is shown by comparing the four compositions in the following table:

Comp. Comp. Comp. Comp. A B C D Ingredient:

Monoethanolammonium thioglycolate, percent Monoethanolammonium dithiodiglycolate, percent. Monoethanolamine, ca, percent Polyoxyethylene lauryl ether with an average of 23 groups per lauryl group, percent Perfume, percent 2.5:1), pereent SiOz (added as sodium silicate having an slot; Nazdratio of Isopropyl myristate, percent Dioetyl phthalate, percent.

Water to make 100% I Total weight, em

Total volume, fl. oz

Propellant (extra):

Monoohlorodifluoroethane, gms-- Dichlorodifluoromethane, gins Difluoroethane, ems

Trifluoromonochloroethane, gnisuse a weak base as a major portion of the alkali, thereby providing desirable buffering capacity. Suitable weak bases have disassociation constants of less than and preferably less than 10*, they include ammonia, monoethanolamine, diethanolarnine, tris(hydroxymethyl)-amin0- methane and 3-amino-2-methyl-l,3-propanediol. Triethanolamine and glycerylamine are further examples of bases which may be used. Monoethanolamine is an especially preferred weak base. When the pH of the lotion is adjusted to the preferred range with a weak base, there will usually be present free base in excess of that required to form the salt of the rnercapto-alkanoic acid. Examples of strong bases which may be used in minor proportions in conjunction with weak bases in this invention are sodium hydroxide, lithium hydroxide, potassium hydroxide, and strong organic bases such as tetramethylammonium hydroxide. Mixtures of weak bases can be employed, and it is often advantageous to do so. Soluble carbonates and bicarbonates, such as ammonium salts, can be added for their pH stabilizing effect. Use of a thioglycolate salt in preparing the lotion is, of course, equivalent to preparing it in situ from thioglycolic acid and the appropriate base.

The keratin-reducing agent is incorporated into the lotion at a level equivalent to from 1 to about 10 weight percent, based on the total composition, of thioglycolic acid. (All percentages used herein are by weight.) The preferred compositions contain keratin-reducing agent at a level equivalent to from about 3% to about 6% thioglycolic acid.

A propellant is required to force the hair waving composition from the pressurized container. While any liquefiable 'gas having the proper vapor pressure and water solubility can be considered, certain fluorinated and chlorinated hydrocarbons have advantageous properties for use in this invention. The selection of the propellant is very important to obtain the desired product characteristics. An important factor in selection of the propellant is its solubility in water. Following is a table of the approximate solubility of a number of propellants in water at 70 F. and at one atmosphere in weight percent:

Propellant: Solubility Dichlorodifluoromethane 0.01 Monochlorodifluoroethane 0.13 Difiuoroethane 0.32 Trifluoromonochloroethane 0.44

It was found that in order to provide a fast breaking It was not practical to compare compositions A, B, C, and D on a completely parallel basis because of marked differences in propellant characteristics. In each composition the waving lotion formulation was the same. Each composition was packaged in a pressurized container fitted with valves to control the discharge of the product and with foam nozzles.

In determining the foam breaking time, each of the four compositions was subjected to prepartory mixing to disperse the propellant in the aqueous phase although such mixing was not necessary for compositions B and D because of the relatively high solubility of their propellants. On discharge from the container, compositions A, B and C formed a sufficient amount of foam, but the foam breaking times of only compositions B and C were satisfactory. Composition D, containing a highly soluble propellant, formed no foam at all, even though it contained as much propellant as composition C and a greater amount of propellant than A or B. The compositions had foam breaking times as follows, determined as described immediately below: 1

A. seconds B. 17 seconds C. 37 seconds D. 0 seconds (no foam) The foam breaking time test consists of the steps of exactly filling a cylinder cup /2 inch high and 1% inches in diameter with foam from a container of the pressurized waving composition and measuring the time taken for the foam to collapse completely to a liquid. The range of desirable foam breaking times, according to this test, is 1045 seconds. This range is substantially equivalent to a range of about 2 to about 10 seconds for the foam to break and soak into a curl when the composition is applied to the hair.

Thus, as regards foam breaking time, only difluoroethane and monochlorodifiuoroethane each when used as the sole propellant provide a deirable product. However, when monochlorodifluoroethane is used as the sole propellant, preparatory mixing of the composition is necessary to obtain satisfactory results. When a vapor pressure depressant is used with monochlorodifluoroethane, the depressant should also be used to balance the densities of the two liquid phases of the composition whereby the two phases are made readily mixable. (The densities of the liquid phases of composition C are so balanced.)

high (125 p.s.i.g. at 70 When difluoroethane is used as the sole propellant, no preparatory mixing is necessary to produce the desired amount of fast breaking foam. When, without preparatory shaking, compositions B, C and D were discharged from their containers, only composition B (containing difluoroethane) produced foam even though it contained a lesser amount of propellant than composition C (wherein the propellant had a lower solubility than difluoroethane) or composition D (wherein the propellant had a greater solubility than difluoroethane).

A further advantageous characteristic that difluoroethane has and which is not possessed by the other propellants listed above is that it is less dense than the aqueous lotion phase and floats thereon. This has the advantage that in a can with the dip-tube leading to the bottom -so that the contents can all be exhausted while the can is in an upright positionthere is no danger of accidentally discharging the propellant without product. Another advantage of difluoroethane is its high degree of hydrolytic stability in the cold waving compositions of this invention. Its stability is slightly better than that of monochlorodifluoroethane.

Monochlorodifluoromethane has solubility characteristics similar to those of difluoroethane and will provide a fast-breaking foam but has a vapor pressure so P. and 320 p.s.i.g. at 130 F.) that it cannot be safely used as the sole propellant even with vapor pressure depressants. Dichloromonofluoromethane has solubility characteristics similar to those of trifluoromonochloroethane, i.e., it is so soluble that it will not provide foam, fast-breaking or otherwise; it is also hydrolytically unstable, particularly in alkaline systems. Other commonly employed chlorofluoro hydrocarbon propellants, such as trichloromonofluoromethane have solubilities which are too low for use in this invention.

It was found that desired propellant solubility characteristics cannot be obtained by blending two or more propellants having high and low solubilities, e.g., trifluoromonochloroethane and dichlorodifluoromethane, in an effort to arrive at a compromise solubility in the desired range. Apparently the foam breaking characteristics imparted to the composition by the propellant are not additive and are determined by the least soluble propellant. However, propellants other than the specified difluoroethane or difluoromonochloroethane propellants can be blended with the specified propellants so long as the desired product characteristics, i.e., fast breaking foam, foam volume and stability are not adversely affected. For example, although monochlorodifluoromethane has a vapor pressure too high to be satisfactorily used as the sole propellant, it may be used in minor amounts with difluoroethane or monochlorodifluoroethane at safe pressures; it may be desirable to use it to raise the density of the propellant mixture or to increase its vapor pressure. Trifluoromonochloroethane, although it is too sluble, as noted above, to provide satisfactory foam characteristics, can be used with difluoroethane or difluoromonochloroethane in minor amounts both as a vapor pressure depressant and as an additional propellant.

When difluoroethane and monochlorodifluoroethane are used in the compositions of this invention in admixture, the product will usually perform in accordance with the characteristics of monochlorodifiuoroethane because of its lower solubility and will require preparatory mixing. Mixing is not necessary if the monochlorodifiuoroethane is present in relatively minor amounts.

The level at which propellant is employed depends upon the propellant chosen, the other ingredients of the composition and the desired pressure in the package. Desirably, from about 2 Weight percent to about 20 weight percent propellant, either difluoroethane or monochlorodifluoroethane is employed. Not less than about 2% is necessary to expel the product in the form of a fast breaking foam. Not more than about 20% should be used in order to avoid too high pressures in the container. When difluoroethane is used as the propellant the preferred amount is in the range of 2.5% to 15%.

A vapor pressure depressant is preferably added to the compositions of this invention to lower the total vapor pressure of the composition and can be used to balance the density of the liquid propellant phase with that of the aqueous phase (i.e., make these two phases substantially equal in density). The latter function is not necessary, however, when difluoroethane is used as the propellant, although it may be done. A vapor pressure depressant suitable for use in this invention must have the following characteristics.

(1) It must be relatively soluble in the propellant and relatively insoluble in the aqueous phase;

(2) It must be stable at the alkaline pH suitable for waving hair;

(3) It must be safe as to toxicity and irritation;

(4) It must be free of undesirable odor and color;

(5) It must not react with the active ingredients of the waving composition; and

(6) It must serve its functions of lowering vapor pressure and, when appropriate, adjusting density.

The vapor pressure depressant may consist of a single compound or it may be a mixture of compounds. The exact amount to be used is the amount Which gives the desired vapor pressure, i.e., a composition vapor pressure not greater than about p.s.i.g. at 70 F and not greater than about 135 p.s.i.g. at F., and, when adjusting density, which balances the density of the aqueous and propellant phases. Such a pressure is suflicient to expel the waving lotion in the form of a satisfactory amount of fast breaking foam Without exceeding the conditions which are preferably observed for safety reasons. It is usually not necessary to depress the vapor pressure of difluoroethane below about 40 p.s.i.g. at 70 F. A vapor pressure below about 90 p.s.i.g. at 70 F. can be obtained Without a vapor pressure depressant. However, a vapor pressure depressant is preferably used in the composition to ensure that the vapor pressure of the composition does not exceed p.s.i.g. at 130 F. This latter condition is desirably observed for safety reasons because temperatures of up to 130 F. or more may be encountered in storage or transit and about 135 p.s.i.g. is the maximum safe pressure for conventional metal containers. The above discussion of preferred vapor pressures is particularly applicable to the usual metal pressurized containers. Lower pressures are preferably observed when using glass pressurized containers.

The quantity of vapor pressure depressant depends upon upon the identity of the depressant and propellant and upon the quantity of propellant; it can constitute from about 1% to about 20% by weight of the total composition. Less has insufficient effect on the pressure, if it is desired to depress the pressure, and more may leave an undesirable oily feel on the hair. The preferred amount of vapor pressure depressant, when used, is about 1% to 10%.

While there are methods available for determining densities of liquid under pressure, a convenient way of ascertaining the amount of vapor pressure depressant required when adjusting the densities of the propellant and aqueous phases, is to slowly add the compound to the otherwise complete system until the propellant phase changes its position, i.e., if it was floating, add until it sinks, or if the aqueous phase was floating, add until it sinks. By performing this test carefully the quantity of vapor pressure depressant required to balance the density of the phases can be determined. Preferably the densities will be adjusted so that the propellant phase just floats. This had the advantage that in a can with the dip-tube leading to the bottom-so that the contents can all be exhausted 9 while the can is in an upright position-th-ere is no danger of accidentally discharging propellant Without product.

Compounds suitable for vapor pressure depressants are organic aromatic and aliphatic carboxylic esters and halogenated propellants having a high solubility in Water and a relatively low vapor pressure. The ester vapor pressure depressants should have a minimum molecular Weight of about 190 because of the low volatility requirement; adequate vapor pressure depressant effect sets a maximum molecular weight for the esters of about 600. The halogenated propellants should have a solubility in water greater than about .05 Weight percent as 70 F. and have a vapor pressure appreciably lower than the specified propellant when used. Desirable compounds for use as vapor pressure depressants include the following:

(1) Dialkyl phthalates where each alkyl radical contains from 2 to 12 carbon atoms; examples are dipropyl phthalate, dihexyl phthalate, ethylbntyl phthalate, and didodecyl phthalate;

(2) Dialkyl glutarates, adipates and pimelates where each alkyl radical contains from 2 to 12 carbon atoms; examples are dioctyl glutarate, didecyl glutarate, ethyl octyl adipate, dihexyl pirnelate, and diethyl pimelate;

(3) Alkyl laurates, myristates and palmitates where each alkyl radical contains from 3 to 8 carbon atoms; examples are octyl laurate, hexyl laurate, propyl myristate, iso-butyl myristate, hexyl palmitate, and pentylpalmitate.

(4) Trifluoromonochloroethane.

Phosphate esters such as tricresyl phosphate have satisfactory physical properties but may have undesirable physiological properties.

Examples of especially preferred compounds for use as vapor pressure depressants include: the dialkyl phthalates, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, and iso-decyl; iso-propyl myristate and palmitate; butyl myristate and palmitate; dioctyl adipate, and trifluoromonochloroethane.

To make clear the manner of choosing a satisfactory combination of propellant and vapor pressure depressant when adjusting the densities of the propellant and aqueous phases, an illustration is given herewith. It is desired to have a product which can be packed in a plastic covered glass container so monochlorodifluoroethane is chosen as a propellant. However, its vapor pressure will not be less than about 29 p.s.i.g. at 70 F.; and since all inert gasses can not be purged from the package, the pressure in the package will be still higher. A pressure less than 25 p.s.i.g. at 70 F. is preferred for glass packaging for safety reasons. An aqueous phase of the desired composition has a density of about 1.03 g. per cc. and the propellant has a density of about 1.12 g. per cc. (both at 70 F.); and, therefore, the propellant sinks to the bottom of the container.

Addition of dioctyl phthalate to give the final composition E, shown below, lowers the vapor pressure suificiently (to about 25 p.s.i.g.); but, as its density is 0.982, it does not lower the density of the propellent, into which it dis.- solves, sufficiently tocause it to float. The two phases differ substantially in density' and remain difliculty dispersible in each other, and when dispersed promptly separate into two phases.

Addition of isopropyl rnyr-istate to give the composition F, lowers the vapor pressure satisfactorily (to 22 p.s.i.g. at 70 F.). Having a low density of 0.85 g. per cc. and dissolving in the propellant, isopropyl myristate causes the propellant phase to float. However, because of a relatively high density differential the two liquid phases are still difiicult to mix and separate promptly when mixed.

Keeping the same total amount of vapor pressure depressant which gave the desired pressure and watching the floating behavior of the propellant phase as the ratio of dioctyl phthalate to isopropyl myristate in the vapor pres- 10 sure depressant is decreased, it is discovered that the pro pellant phase floats when the final composition. is G and that the densities of the aqueous and propellant phases are substantially equal.

Percent Ingredient Comp.E Comp. F Comp. G-

Monoethanolammonium thiglycolate 8. 0 8. 0 8. 0 Monoethanolammonium dithiodiglycolate 3. 2 3. 2 3. 2 Monoethanolamine, ca 2. 3 2. 3 2. 3

Polyoxyethylene lauryl ether with an average of 23 oxyethylene groups per lauryl group 1. 0 1. 0 1. 0 Perfume 1. 0 1. 0 1. 0 Dioctyl phthalate... 4. 6 0. 0 3. 0 Isopropyl myristate- 0. 0 4. 6 1. 7 Monoehlorodifluoroethane 7. 0 7. 0 7. 0 Water Bal. Bal. Bal.

Percent Percent Location of "lime, isopropyl dioctyl propellant minutes Comp. myristate phthalate phase 4. 6 0. 0 4 F 2. 1 2. 5 20 H 1. 7 3. 0 25 G- 1. 5 3. 2 40 I 0. 0 4. 6 8 E 1 Time required for phase separation resulting in poor quality foam.

Among the several compositions, composition G is the choice for commercial use. The densities of phases are almost exactly balanced in I but the exact control of proportions required to insure that the propellant floats is not economical in commercial production. At 1.3% isopropyl myristate and 3.4% dioctyl phthalate the propellant phase sinks.

Difluoroethane can be employed if the composition is to be packed in a metal can and a higher pressure is desired. This propellant has a higher vapor pressure than monochlorodifluoroethane and its density is about 0.911 g. per cc. Dibutyl phthalate, having a density of 1.04 g. per cc., is slowly added to an aqueous. composition like that of E, but with difluoroethane propellant, until the floating propellant phase just sinks. It is then known that the correct quantity of dibutyl phthalate is just a little less than that employed and this is confirmed by making a solution of composition K. The propellant phase floats and the density of the propellant phase is almost equal to that of the liquid phase. The two phases readily disperse on shaking and will remain dispersed without further shaking for about 20 minutes.

In summary, when adjusting the density of the propellant and aqueous phases, the vapor pressure depressant to go with a particular propellant is composed of an ester or esters in amount to give the desired lowering of vapor pressure. The vapor pressure depressant is selected according to the relative density of the esters and the propellant to make the density of the propellant phase substantially equal to the density of the aqueous phase. Densities of propellants and esters are found in the printed literature.

A surface active agent is included in the compositions of this invention. Its presence enables the achievement of a stiff dry' fast breaking foam. Fast breaking is intended to mean a foam which breaks in less than 40 seconds, and preferably in about 2 to about seconds, after discharge onto the hair. If too much surface active agent is employed the foam tends to break too slowly; enough must be used to achieve desirably thick foam. Suitable surface active agents are found among the anionic detergents and among nonionic detergents. In the case of anionic detergents, it is preferred that the cation of the detergent be one which confers high solubility on the detergent; with this limitation, the cations of the alkalizing agents listed hereinbefore may be used. The choice of a surface active agent is not critical, most of those commonly employed in shampoos and other personal products being satisfactory.

Examples of anionic synthetic detergents suitable for the practice of this invention are the detergents of the sulfonated and sulfated types such as the alkyl (C -C sulfates, the alkyl (C C polyethenoxy (1-10 units of -C H O) ether sulfates, the alkyl (C -C aromatic sulfonates, the monoor di-alkyl (C -C esters of sulfosuccinic acid, sulfonated or sulfated amides of higher fatty acids, sulfuric acid esters of polyhydric alcohols incompletely esterified with higher fatty acids, higher fatty acid esters of low molecular weight alkylol sulfonic acids, etc., usally in the form of their sodium, potassium, ammonium, or lalkanolammonium salts. Some of the particular detergents of this category are sodium octyl sulfate, sodium nonyl sulfate, sodium decyl sulfate, mono-ethanolammonium dodecyl sulfate, ammonium tetradecyl sulfate, monoethanolammonium pentadecyl sulfate, monoethanolammonium hexadecyl sulfate, monoethanolammonium octadecyl sulfate, monoethanolammonium oleyl sulfate, sodium salts of dioctyl sulfosuccinate, sodium octyl benzene sulfonate, sodium nonyl benzene sulfonate, sodium dodecyl benzene sulfonate, sodium tetradecyl benzene sulfonate, ammonium pentadecyl benzene sulfonate, ammonium triisopropyl benzene sulfonate, sodium salts of the oleic acid ester of isethionic acid, sodium salt of the lauric acid amide of taurine, triethanol-ammonium coconut oil monoglyceride monosulfate, monoethanolammonium tallow diglyceride monosulfate.

Mixtures of various of the anionic synthetic detergents also come within the scope of the general class definition above. For example, the commercially available detergents are generally not pure compounds but are mixtures of homologous compounds. Thus, sodium alkyl benzene sulfonate wherein the alkyl group contains 12 to 18 carbon atoms, a mixture of triethanolammonium alkyl sulfates consisting mostly of triethanolammonium lauryl sulfate, and a mixture of monoethanolammonium polyethenoxy ether sulfates wherein the alkyl group contains from 12 to 18 carbon atoms and there are from 1 to 6 units of -C H O per molecule, are well known detergents. As a further example of commercially important mixtures, alkanolammonium salts of coconut sulfate and coconut polyethenoxy ether sulfate are among the detergents which are highly suitable for use in this invention. The coconut alkyl radical is derived from the middle distillation cut and typically will contain the following appropriate percentages of various chain lengths: C -2%, Cur-66%, C14-23% and C169%.

Water soluble soaps of fatty acids, such as sodium, potassium, ammonium or triethanol amine salts of tallow or coconut oil fatty acid, may be used, but the synthetic detergents are preferred. When waving lotion containtypes,

wherein R represents long chain alkyl radicals having from about 8 to about 18 carbon atoms and n is an integer from about 4 to about 30; the polyethylene oxide condensates of alkyl phenols, e.g., the condensation products of alkyl phenols having about 6 to 12 carbon atoms in the alkyl group, in either straight chain or branched chain configuration, with ethylene oxide in amounts equal to 10 to 25 moles of ethylene oxide per mole of alkyl phenol; compounds formed by condensing ethylene oxide with a hydrophobic base formed by the condensation of propylene oxide with propylene glycol; the condensation product of ethylene oxide with the product resulting from the reaction of propylene oxide and ethylene diamine. Compounds with ether linkages are preferred because of their resistance to hydrolysis in alkaline solutions. More specific examples of some suitable non-ionic detergents are: the reaction products of t-octylphenol with an average of from 9 to 30 moles of ethylene oxide per mole, and the watersoluble waxy reaction products of lauryl alcohol and ethylene oxide having a titer of about 35 C. or higher and of oleyl alcohol and ethyleneoxide having a titer of about 29 C. or higher.

The quantity of surface active agent employed is from about 0.05% to about 2%. The surface active agent serves the primary purpose of contributing tothe production of a foam having the desired characteristics; it also aids in solubilizing or emulsifying the perfume and contributing to the solubilization of the propellant. In such proportions the surface active agent does not have the disadvantages mentioned in connection with emulsifiers hereinbefore, i.e., a decrease of mildness of the Waving lotion, possible interaction with the Waving agent and a tendency for poor waving results.

Various minor ingredients can be included in the compositions of this invention and are generally desirable for the purposes of making the product more pleasant to use and leaving the hair in a particularly good condition. It is generally desirable to include a soluble salt of the disulfide of the keratin-reducing agent, especially the disulfide of thioglycolic acid, at a level, based on the total composition, equivalent to from about 0.5% to 5% of dithiodiglycolic acid. The soluble salts which can be used include those formed from the bases listed as suitable for making the pH adjustment. These additives protect the hair from over-treatment and leave it in a particularly good condition as is disclosed in US. Patents 2,719,814 and 2,719,815. A perfume will be added in the preferred compositions of this invention.

The compositions of this invention must be packaged in suitable pressure-tight containers. For pressures lower than about 25 p.s.i.g. at 70 F., glass bottles, which are coated on the outside with plastic and metal cans are suitable. Metal cans are preferably employed for higher pressures. A metal which is not appreciably corroded by the product should be chosen and/ or a corrosion inhibitor should be added to the formulation. Aluminum cans are preferred because of their lightness, economy and resistance to corrosion. When aluminum cans are used, it is particularly desirable to include in the waving lotion, as a corrosion inhibitor, from about .001% to about 0.1%

13 SiO as Water soluble sodium silicate. Water soluble sodium silicates having a weight ratio of SiO :Na O in the range of about 5 :1 to about 1:1 are quite satisfactory.

The valves, with which the pressurized containers are fitted to control their opening and discharge of product, are those commercially employed for other aerosol products. Nozzles for discharge of the product are not critical except that it is preferred to use a foam type nozzle. This type of nozzle provides opportunity for an appreciable pressure drop while the product is still confined within the nozzle. This pressure drop within the enclosed channel causes foam to be generated Within the nozzle. Foam nozzles are commercially available and have been repeatedly described in the literature. For example, the US. Patent 2,655,480 of Spitzer et a1. shows a typical foam nozzle. For additional convenience a comb-type applicator which discharges the foam from its teeth over the Width of the tress can be used on the nozzle.

In the following, specific examples are set forth as illustrative of the invention and of certain of the relationships important in its practice. Compositions are expressed in weight percent.

Example I The following composition was prepared and intro duced into pressurized aluminum cans fitted with valves to control the discharge of the product and with foam nozzles.

Polyoxyethvlene lauryl ether with an average of 23 oxyethylene groups per lauryl group 0.95

Perfume 0.95

SiO- (added as sodium silicate having an sio zNa O ratio of 2.5:1) 0.01

Water Bal.

The nronoethauolammonium thioglycolate in this composition is equivalent to about 4.5% thioglycolic acid. Monoethanolammonium dithiodiglycolate, perfume and sodium silicate while having a desirable effect on the product, are not essential to the success of the present invention.

This composition gave a pressure of 60 p.s.i.g. at 70 F. and 11S p.s.i.g. at 130 F. and discharged from the container in the form of a thick, dry, fast-breaking foam. There was no necessity for preparatory mixing. The time required for substantially complete collapse of the foam on the hair was about 5 seconds. The propellant floated on the aqueous phase. When used in waving hair, it gave results fully as good as leading commercial waving preparations; and it had the advantage of being easy to apply neatly without run-ofi of excess lotion.

The following vapor pressure depressants were subtituted for the isopropyl myristate in the composition of Example I in substantially equal amounts with substantially equal results: diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, didecyl phthalate, isopropyl palmitate, butyl myristate, dioctyl glutarate, dihexyl pimelate and dioctyl adipate.

The level of monoethanolarnrnonium thioglycolate can be increased to the equivalent of 7% thiogiycolic acid to give a very curly wave While retaining the advantages of this invention; or it can be reduced to the equivalent of 3% thioglycolic acid to give a very loose and casual wave while retaining the advantages of this invention. Ammonia, tr-is(hydr.oxymethyl)aminomethane, 2-amino-2- methyl-1,3-propaned-iol and diethanolamine can replace monoethanolamine, in whole or in part, and pH adjustment can be from pH 8.5 to pH 9.5 in this example without losing its advantages.

Example 11 The following composition was prepared and packed in a pressurized aluminum can fitted with a valve to control the discharge of the product and a foam nozzle.

Polyoxyethylene lauryl ether with an average of 23 oxyethylene groups per lauryl group 0.95 Perfume 0.95 SiO (added as sodium silicate having an SiO :Na O ratio of 2.5:1) 0.01 Water Bal.

The vapor pressure of this composition was 60 p.s.i.g. at 70 F. and p.s.i.g. at F. The composition discharged from the foam nozzle as a thick, dry foam which collapsed on the hair in about 5 seconds. There was no need for preparatory mixing. The propellant phase was lower in density than the aqueous phase and floated thereon. The composition proved effective in waving hair and left the hair in good condition.

The nonionic detergent in this composition can be replaced by any one of the following detergents at the level indicated while retaining the advantages of this invention: tn'ethanolamine lauryl polyethenoxy other sulfate in which the average number of ethenoxy groups per molecule is about 3-0.5%; triethanolamine lauryl sulfate-0.5%; alkylaryl polyether alcohol (the reaction product of toctylphenol with an average of 910 moles of ethylene oXide)-0.05

Example III The following composition was prepared and introduced into pressurized plastic-covered glass bottles fitted with valves to control the discharge of the product and with foam nozzles.

Polyoxyethylene lauryl ether with an average of 23 oxyethylene groups per lauryl group 0.93 Perfume 0.93 Sodium silicate having an SiO :Na O ratio of 2.5 :1 0.03 Water Bal.

The monoethanolammonium thioglycolate in this composition is equivalent to about 4.6% thioglycolic acid. Monoethanolammonium dithiodiglycolate, perfume and sodium silicate, While having a desirable effect on the product, are not essential to the success of the present invention.

This composition gave a pressure of 23 p.s.i.g. at room temperature and discharged from the container in the form of a thick, dry, fast-breaking foam. The time required for substantially complete collapse of the foam in the cup test was about 35 seconds. The two phases stayed sufficiently well mixed after shaking so that foam of the desired properties was obtained for about 25 minutes. On separation the propellant floated on the aqueous phase. When used in waving hair, it gave re- 15 suits fully as good as leading commercial waving preparations; and it had the advantage of being easy to apply neatly without run-off of excess lotion.

The level of monoethanolammonium thioglycolate can be increased to the equivalent of 7% thioglycolic acid to give a very curly wave while retaining the advantages of this invention; or it can be reduced to the equivalent of 3% thioglycolic acid to give a very loose and casual wave While retaining the advantages of this invention. Ammonia, tris(hydroxymethyl)amino-methane, 2-amino-2-methyl 1,3 propanediol and diethanolamine can replace monoethanolamine, in whole or in part, and pH adjustment can be from pH 8.5 to pH 9.5 in this example without losing its advantages.

Example IV The following composition was prepared and packed in a pressurized aluminum can fitted with a valve to control the discharge of the product and a foam nozzle.

Polyoxyethylene lauryl ether with an average of 23 oxyethylene groups per lauryl group 0.93 Perfume 0.93 Sodium silicate having an SiO :Na O ratio of 2.5 :1 Water 0.03 Bal.

The vapor pressure of this composition was about 43 p.s.i.g. at room temperature. The composition discharged from the foam nozzle as a thick, dry foam which collapsed in the cup test in about 20 seconds. The propellant phase was slightly lower in density than the aqueous phase, but after agitation they remained sufficiently dispersed in each other for at least 15 minutes. The composition proved effective in waving hair and left the hair in good condition.

The nonionic detergent in this composition can be replaced by any one of the following detergents at the level indicated while retaining the advantages of this invention: triethanolamine lauryl polyethenoxy ether sulfate in which the average number of ethenoxy groups per molecule is about 3O.5%; triethanolamine lauryl sulfate0.5%; alkylaryl polyether alcohol (the reaction product of t-octylphenol with an average of 910 moles of ethylene oxide)-0.05%.

Example V A composition as described below was prepared and packed in a pressurized plastic covered glass bottle fitted with a valve to control the discharge of product and a foam nozzle. The composition was that of Example III except that: the level of dioctyl phthalate was raised to 8.10%; the level of isopropyl myristate was raised to 4.60%; and the level of monochlorodifiuoroethane was raised to 18.6%. The amount of water was decreased correspondingly. This composition without the vapor pressure depressants would exert a pressure of greater than 29 p.s.i.g., depending on the thoroughness of purging. The composition with the vapor pressure depressant exerted a vapor pressure of 22 p.s.i.g. at room temperature. The propellant phase floated on the aqueous phase and was readily dispersible by shaking. The phases stayed sufliciently dispersed to give a good dry thick foam for periods up to about one-half hour.

10 The foam breaks to a liquid in about 30 seconds in the cup test.

This composition waved hair effectively and left the hair in good condition. It combined the performance of a conventional Waving lotion With the conveniences inherent in the compositions of this invention.

Example VI The following composition was prepared and packaged in a plastic covered glass bottle fitted with a valve and a foam nozzle. The propellant phase floated on the aqueous phase.

Polyoxyethylene lauryl ether with an average of 23 oxyethylene groups per lauryl group 0.93

Perfume 0.93 Sodium silicate having an SiO :Na O ratio of 2.5 :1 0.03 Water Bal.

Example VII The following composition was prepared and packaged in a plastic covered glass bottle fitted with a valve and a foam nozzle.

Ingredients: Percent Monoethanolammonium thioglycolate 7.7 Monoethanolammonium dithiodiglycolate 3.1 Monoethanolamine (to adjust pH to 9.3) 2.1 Isopropyl myristate 4.8 Trifluoromonochloroeth'ane 3.5 Monochlorodifluoroethane 3.5

Polyoxyethylene lauryl ether with an average of 23 oxyethylene groups per lauryl group 0.93

Perfume 0.93

Sodium silicate having an SiO :Na O ratio of Water Ba].

Example VIII The following compositions were prepared and packaged each in an aluminum can fitted with a valve and a foam nozzle.

L M N Ingredients:

Monoethanolamine thioglycolate, percent 7. 7 7. 7 7.7 Monoethanolamine dithiodiglycolate,

percent 3.1 3.1 3.1 Monoethanolamine, percent 2.1 2.1 2.1 Monochlorodifiuoroethane, percent 7.0 3. 5 Difluoroethane, percent 3. 5 7. Polyoxyethylene lauryl ether with an average of 23 oxyethylene groups per lauryl group, percent 0.93 0. 93 0. 93 Perfume, percen 0. 93 0. 93 0. 93 Sodium silicate having an SlOgZNEzO ratio of 2.51, percent 0.03 0. 03 0. 03 Water to make 100% Bal. Bal. Bel.

Characteristics:

Composition vapor pressure at 70 F.,

p.s.i.g 30 54 62 Foaming breaking speed (cup test), in

seconds 35 30 18 Preparatory mixing re ired to obtain thick dry foam Yes Yes No Propellant layer location Bottom Top Top These formulas are well adapted ior waving hair with the advantages of manipulation inherent in the fast-breaking foam of this invention. The pmessurized compositions of this example can be safely employed without a vapor pressure depressant; however, when doing so it would be desirable to avoid unusually high temperatures unless containers somewhat stronger than the ordinary containers are used.

In the case of compositions L and M (containing monoohlorodifiuonoethane) the dispersion of rthe propellant in the aqueous phase persisted and gave good, past-breaking foam for about 20 minutes. However, if a vapor pressure depressant had been used, it would have been necessary to balance the densities of the liquid phases to obtain such persistance of dispersion and ioarn.

This application is a continuation-in-part of copending application Serial No. 839,282, filed September 11, 1959, now abandoned.

So far as the waving ingredients of the this invention are concerned, they are conventional and no claim is made to them per se.

What is claimed is:

1. A two liquid phase pressurized hair waving composition adapted for discharge from its container as a foam, which collapses to a liquid promptly after discharge, consisting essentially of: from about 1% to about 10% of a low molecular weight mercapto-alk-anoic acid, an alk-aiizing agent a substantial part of which is a base with a dissociation constant less than 10* imparting to the composition a pH above about 7 but below 10; from about 2% to ab out 20% of a propellant selected from the group consisting of difluoroethane and monochl-orodifluoroethane; as a vapor pressure depressant inom about 1% to about 20% of an onganic compound selected from the group consisting of: dialkyl p-hthalates, glutanates, adipates and pimelates wherein the alkyl group contains 2 to 12 carbon atoms, alkyl laurates, myristates, and palmitates wherein the alkyl radical contains from 3 to 8 carbon atoms, and mixtures thereof, said organic compound being present at a level such that the vapor pressure of the composition is less than about 135 =p.s.i.g. at 130 F., and, when monochlorodiiiuoroethane is the propellant, such that the density of the propellant phase is substantially equal to the density of the aqueous phase, the two liquid phases thereby being made readily mixab-le; from about 0.05% to about 2% of a surface active agent selected from the group consisting of nonionic and anionic surface active agents; and the balance substantially water.

2. A two liquid phase pressurized hair waving composition adapted for discharge from its container as a foam, which collapses to a liquid promptly afiter discharge, consisting essentially oi: from about 1% to about 10% of a low molecular weight mercapto-alkanoic acid, an alkalizing agent a substantial part of which is a base with a dissociation constant less than 10- imparting to the comcompositions of A position a pH of from 8.5 to 9.5; as a propellant, not less than about 2.5% and not more than about 15% difluoroethane; as a vapor pressure depressant, from about 1% to about 20% of an organic compound selected from the group consisting of: dialkyl phthalates, glutanates, adipates, and pimelates wherein the alkyl group contains 2 to 12 carbon atoms, alkyl laurates, myristates, and palmitates wherein the alkyl radical contains from 3 to 8 carbon atoms, and trifluoromonoehlonoethane, said organic compound being present at a level such that the vapor pressure of the composition is not greater than about 135 p.s.i.g. at F.; from about 0.05% to about 2% of a surface active agent selected from the group consisting of nonionic and anionic surface active agents; and the balance substantially water.

3. The composition of claim 2 wherein the vapor pressure depressant is isopropyl my-ristate.

4. A pressure tight aluminum container which contains the composition of claim 2, said composition containing addition-ally, as a corrosion inhibitor, from about .001% to about 0.1% SiO added as water soluble sodium silicate.

5. A two liquid phase pressurized hair waving composition adapted for discharge from its container as a team, which collapses to a liquid promptly after discharge consisting essentially of: from about 3% to about 6% of thioglycolic acid, an alkalizing agent, a substantial part of which is a base selected from the group consisting of ammonia, monoethanolarnine, diet-hanolamine, tris(hydroxymethyl) aminomethane, 2-armino-2-methyl 1,3 propane diol and mixtures thereof imparting to the composition a pH of about 9.3; as a propellant, not Hess than about 2.5% and not more than about 15% difluoroethane; as a vapor pressure depressant from about 1% to about 10% of an organic compound selected from the group consisting of: dialkyl phthalates, glutarates, ladipates, and pimelates wherein the alkyl group contains 2 to 12 carbon atoms, alkyl laurates, myristates and palmitates wherein the alkyl radical contains from 3 to 8 carbon atoms, and mixture thereof, said organic compound being present at a level such that the vapor pressure of the composition is not greater than about psig. :at 130 F.; and from about 0.05% to about 2% of a surface active agent selected from the group consisting of nonionic and anionic surface active agents; and the balance substantially water.

6. The composition of claim 5 wherein the vapor pressure depressant is isopropylmyristate.

7. A pressure tight aluminum container which contains the composition of claim 5, said composition containing additionally, as a corrosion inhibitor, from about .001% to about 0.1% SiO added as water soluble sodium silicate.

8. A two liquid phase pressurized hair waving composition adapted for discharge from its container as a foam, which collapses to a liquid promptly after discharge, consisting essentially of: from about 1% to about 10% of a low molecular weight mercapto-alkanoic acid, an alkalizing agent a substantial part of which is a base with a dissociation constant less than 10* imparting to the composition a pH of from 8.5 to 9.5; as a propellant, from about 2% to about 20% of difluoroethane; as a vapor pressure depressant and density balancer, from about 1% to about 20% of organic esters selected from the group consisting of: dialkyl phthalates, glutarates, adipates, and

pimelates wherein the alkyl group contains 2 to 12 carbon atoms, alkyl laurates, myristates, and palmitates wherein the alkyl radical contains from 3 to 8 carbon atoms, and mixtures thereof, said esters being selected according to their density relative to the propellant and being present at a level such that the density of the propellant phase is substantially equal to the density of the aqueous phase, the two liquid phases thereby being made readily mixable; from about 0.05% to about 2% of a surface active agent selected from the group consisting of nonionic and anionic surface active agents; and the balance substantially water.

9. The composition of claim 8 wherein the vapor presposition adapted [for discharge from sure depressant and density balancer is' dibutyl phthalate.

10. A twoliquid phase pressurized hair waving composition adapted for discharge from its container as a foam, which collapses to a liquid promptly after discharge, consisting essentially of from-about 1% to about-10% of a low molecular weight mercapto-alkanoic acid, an alkalizing agent a substantial part of which is abase with a dissociation constant less than 10* imparting to; the composition a pH of from 8.5 to 9.5; as a propellant, from about 2% to about 20% monochlorodifiuoroethane; as a vapor pressure depressant and density balancer, from about 1% to about 20% of organic esters selected from the group consisting of: dialkyl ph thalates, glutarates, adipates, and pimelates wherein the alkyl group contains 2 to 12 carbon atoms, alkyl laurates, myristates and palmitates wherein the alkyl radical contains from 3 to 8 carbon atoms, and mixtures thereof, said esters. being selected according to their density relative to the propellant and being present at a level such that the density of the propellant phase is substantially equal to the density of the aqueous phase, the two liquid phases thereby being made readily mixable; from about 0.05% to'about 2% of a surface active agent selected from the group consisting of nonionic and anionic surface active agents; and the balance substantially water.

11. The composition of claim 10 wherein the vapor pressure depressant and density balancer is a mixture of isopropyl myristate and dioctyl phthalate.

12. A two liquid phase pressurized hairwaving comits container as a foam, which collapses to a liquid promptly after discharge, consisting essentially of: from'abou't 3% to about 6% of thioglycolic acid, an alkalizing agen -a substantial part of which is a base selected fromthegroup consisting of ammonia, monoetlranolamiine, diethanolamine, tris(h'ydroxymethyDaminomethane, 2 amino-2-methyl-L3-pr'opanediol and mixtures thereof imparting to-the composition a pH of about 9.3; as a propellant, from about2% to about of difiuoroethane;-as a vapor pressure depressant and density balancer, from about 1% to about 20% of dibutyl phthalate, said dibutyl phthalate being present at a level such that the density ofthe propellant phase is substantially equal to the-density of the aqueous phase, the two liquid phases thereby being made readily mixable; and from about 0.05% to about 2% of a surface active agent selected from the group consisting-of nonionic and anionic surface active agents; and-the balance substantially water. I

13. Av two liquid phase pressurized hair waving composition adapted for discharge" from itscontaliner as a foam, which collapses to a liquid promptly after discharge, consistingessentially of: from about3% to about-6% of thioglycolic acid, an-alkalizing agent a substantial part'of which is a base selected from the" group consisting of ammon ia, monoethanolamine, diethanolamine, tris(hydroxymethyDaminomethane, 2-amino-2-m'ethyl 1,3-propanedi'ol and mixtures thereof imparting to the composition a pH of about 9.3; a propellant, from about 2% to about asa vapor pressure de"- 0% of a mixture of isopropyl m-yni'state and dioctyl phthalate, said mixture beingpresen-tat-a level such that the density of the propellant phase is substantially equal to the density of the aqueous phase, the two liquid phases thereby being made readily mixable; and from about 0.05 to about 2% of a surface active agent selected from the group consisting of nonionic and anionic surface active agents; and the balance substantially water.

14. A two liquid phase pressurized hair waving composition adapted for discharge from its container as a foam, which collapses to a liquid promptly after discharge, consisting esesntially of: from about 1% to about 10% of a low molecular weight mercapto-alkanoic acid, an alkalizing agent a substantial part of which is a base with a disass'oc'iation constant less than 10 imparting to the composition a pH above about7 but below 10; from about 2% to about 20% of a propellant selected from the group consisting of difluoroethane and monochloroclifluoroethane; fioin about 0.05% to about 2% of a surface active agent selected from the group consisting of nonionic and anionic surface active agents; and the balance substantially water.

15. The composition of claim 14 which contains, as a vapor pressure depressant, about 1% to about 20% trifiuoromonocliloroethane and sufiic-ient in amount that the vapor pressure of the composition is not greater than about 135 p.s.i.g. at F.

16. A two liquid phase pressurized hair waving composition adapted for discharge from its container as a foam, which collapses to a liquid promptly after discharge, consisting essentially of: from about 3% to about 6% of thioglycolic acid, an alkalizing agent, a substantial part of which is a base selected from the group consisting of ammonia, monoethanolamine, diethanolamine, tris(hydroxymethyl) aminomethane, 2-amino-2-methyl-1,3-propanedioland mixtures thereof imparting to the composition a pH in the range of 8.5 to 9.5; from about 2% to about 20% of aprope'llant selected from the group consisting ofdifluoroethane and monochlorodifluoroethane; from about 0.05 to about 2% of a surface active agent selected'from-the group consisting of nonionic and anionic surface'activeagents; and the balance substantially water.

17. The composition of claim 16, which contains as a vapor presure depressant, about 1% to about'20% trifluoromonochloroethane and sufficient in amount that'the vapor pressure of the composition is not greater than about 1'35v p.s.i.g.' at'130 F.

References Cited in the file of this patent UNITED STATES PATENTS Richardson Sept. 27, 1955 

1. A TWO LIQUID PHASE PRESSURIZED HAIR WAVING COMPOSITION ADAPTED FOR DISCHARGE FROM ITS CONTAINER AS A FORM WHICH COLLAPSES TO A LIQUID PROMPTLY AFTER DISCHARGE, CONSISTING ESSENTIALLY OF: FROM ABOUT 1% TO ABOUT 10% OF A LOW MOLECULAR WEIGHT MERCAPTO-ALKANIOC ACID, AN ALKALIZING AGENT A SUBSTANTIAL PART OF WHICH IS A BASE WITH A DISSOCIATION CONSSTANT LES THAN 10-5 IMPARTING TO THE COMPOSITION A PH ABOVE ABOUT 7 BUT BELOW 10; FROM ABOUT 2% TO ABOUT 20% OF A PROPELLANT SELECTED FROM THE GROUP CONSISTING OF DIFLUOROETHANE AND MONOCHLORODIFLUOROETHANE; AS A VAPOR PRESSURE DEPRESSANT FROM ABOUT 1% TO ABOUT 20% OF AN ORGANIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF: DIALKYL PHTHALATES, GLUTARATES, ADIPATES AND PIMELATES WHEREIN THE ALKYL GROUP CONTAINS 2 TO 12 CARBON ATOMS ALKYL LAURATES, MYRISTATES, AND PALMITATES WHEREIN THE ALKYL RADICAL CONTAINS FROM 3 TO 8 CARBON ATOMS, AND MIXTURE THEREOF, SAID ORGANIC CCOMPOUND BEING PRESENT AT A LEVEL SUCH THAT THE VAPOR PRESSURE OF THE COMPOSITION IS LESS THAN ABOUT 135 P.S.I.G. AT 130*F., AND WHEN MONOCHLORODIFLUOROETHANE IS A PROPELLANT, SUCH THAT THE DENSITY OF THE PROPELLANT PHASE IS SUBSTANTIALLY EQUAL TO THE DENSITY OF THE AQUEOUS PHASE, THE TWO LIQUID PHASE THEREBY BEING MADE READILY MIXABLE; FROM ABOUT 0.05% TO ABOUT 2% OF A SURFACE ACTIVE AGENT SELECTED FROM THE GROUP CONSISTING OF NONIONIC AND ANIONIC SURFACE ACTIVE AGENTS; AND THE BALANCE SUBSTANTIALLY WATER. 